Fill a small saucepan 1/3 full with water. Bring to a simmer, and place the bowl of curd on top of it. Stir constantly, heating the curd slowly, working to 166F over ten minutes. Pull the curd from the heat when it is thick enough to coat your spoon, it will thicken substantially as it cools. Keep refrigerated for up to a week, or up to a month in the freezer.